浸没式离子交换-微滤组合膜的膜污染分析

Membrane Fouling Analysis of Immersion IE-MF Composite Membrane

针对浸没式离子交换-微滤(IE-MF)组合膜分离浓缩低C/N生活污水氨氮的过程中产生的膜污染问题,采用X荧光光谱、X射线衍射及电感耦合等离子质谱等技术对主要污染物成分进行了分析,并考察了膜污染机理。结果表明,微滤膜端滤饼层的晶体结构属针铁矿类,主要成分是Fe(OH)_3及少量的Fe CO_3、Mg CO_3等物质,离子交换膜内表面沉积物主要为Ca、Mg、Fe的碳酸盐等物质。滤饼层是由电极电解反应产生的Fe(OH)_3胶体与Ca、Mg等碳酸盐及其他固体杂质相互吸附聚集沉积在微滤膜表面所形成的;离子交换膜内表面沉积物为电解反应产生的OH^-使离子交换膜内表面碱化,引起Fe^(3+)、Ca^(2+)、Mg^(2+)等阳离子在离子交换膜内表面与相关阴离子结合生成附着于膜表面的沉淀而形成的。

In order to figure out the membrane fouling problem of immersion IE-MF （ion exchange and micro-filtration） composite membrane in the process of separating and enriching ammonia nitrogen from domestic sewage of low C/N ratio, X-ray fluorescence, X-ray diffraction and inductively coupled plasma were used to analyze the fouling composition and mechanism. The results showed that, the crystal structure of filter cake layer on microfiltration membrane belonged to goethite, which mainly consisted of Fe（OH）3 and a small amount of FeCO3, MgCO3 and so tbrth. The main ingredients of sediments on the internal surface of cation exchange membrane were Ca, Mg and Fe carbonate. The fbrming process of filter cake layer was considered as Fe（OH）3 colloid generated by electrochemical reaction would adsorb Ca, Mg, Fe carbonate and other solid impurities and then deposited on the surface of micro- filtration membrane. Meanwhile, the forming process of sediments on the internal surthce of cation exchange membrane was considered as extral OH- generated by electrochemical reaction would alkalify the internal surthce of cation exchange membrane, thus leading cation nearby such as Fe3＋, Ca2＋ and Mg2＋ combined with matched anion to form sediments which attached to the internal surface of membrane.